JP3934447B2 - Automatic paper feed mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic paper feeding mechanism that separates stacked sheets one by one and feeds them to a post-processing section (printing section or reading section of a printer or scanner). A paper feed roller that comes into contact with the outer surface of the paper sheet and feeds out the paper sheet on the outer surface, and is arranged in a state where it is urged toward the outer peripheral surface of the paper feed roller at the paper sheet feed position by the paper feed roller In addition, the present invention relates to an automatic paper feed mechanism including a friction pad that contacts a paper sheet fed out simultaneously with an outer paper sheet and prevents a plurality of paper sheets from being simultaneously fed out by a frictional force.
[0002]
[Prior art]
FIG. 6 is a side view showing a main part of a conventional automatic paper feeding mechanism in a printer, a scanner or the like, and FIG. 7 is a front view seen from the right direction in FIG. In these drawings, paper sheets 10 are stacked on a paper feed table 30. The paper feed table 30 is biased upward (in the direction of arrow A) by a pressing means such as a spring (not shown), and the uppermost paper sheet 11 in the paper sheets 10 is pressed against the outer peripheral surface of the paper feed roller 20. Has been. Thereby, the paper feed roller 20 can feed out the uppermost paper sheet 11 by rotating counterclockwise (B direction) in FIG.
[0003]
The paper feed roller 20 includes a cylindrical collar portion 21 that is locked to a drive shaft 40 that rotates in the direction of arrow B, and a rubber ring 22 that is fitted to the outer cylindrical surface of the collar portion 21. . A friction pad 50 is disposed at a sheet feeding position by the sheet feeding roller 20. The friction pad 50 comes into contact with the paper sheet 10 delivered simultaneously with the uppermost paper sheet 11, and prevents a plurality of paper sheets 10 from being simultaneously fed out by a frictional force.
[0004]
As the friction pad 50, generally, the friction coefficient between the friction pad 50 and the paper sheet 10 is slightly higher than the friction coefficient between the paper sheets 10, and between the paper feed roller 20 and the paper sheet 10. A material having a value lower than the friction coefficient is used, and as a material, an EPDM rubber plate, a foamed urethane rubber plate, a cork plate or the like having a JIS-A hardness of about 70 degrees is often used. The friction pad 50 is supported so as to be movable in the direction of the outer peripheral surface of the paper feed roller 20 (in the direction of arrow C), and is further biased toward the outer peripheral surface of the paper feed roller 20 by a pressing means such as a spring (not shown). .
[0005]
Next, the operation of the conventional automatic paper feeding mechanism will be described with reference to FIG. When the paper feed roller 20 is rotated in the arrow B direction by a rotation drive source such as a motor (not shown), the uppermost paper sheet 11 in contact with the paper feed roller 20 advances in the transport direction (arrow D direction). . At this time, the second paper sheet 12 also moves in the transport direction due to the frictional force between the paper sheets 10, and in some cases, the third paper sheet is also dragged to the second paper sheet 12. Move in the transport direction. The tips of the plurality of paper sheets 10 come into contact with the friction pad 50.
[0006]
In this state, for the uppermost paper sheet 11, the conveying force applied from the paper feed roller 20 is larger than the total frictional resistance force from the friction pad 50 and the second sheet of paper 12. It proceeds in the direction (arrow D direction). However, in the second and subsequent sheets 10, the conveying force applied from the uppermost sheet 11 is smaller than the total frictional resistance force from the friction pad 50 and the third sheet, It stops at the position where it contacts the friction pad 50. By the above operation, only the uppermost paper sheet 11 out of the paper sheets 10 is fed out. After that, when the rear end of the topmost sheet 11 is pulled out from below the paper feed roller 20, the same feeding operation as described above is repeated to feed only the next topmost sheet. I will do paper.
[0007]
[Problems to be solved by the invention]
In such an automatic paper feeding mechanism, only one sheet is fed out from the stacked paper sheets due to the difference in the friction coefficient between the members, so that the paper sheets, the paper sheets and the friction pads, the paper sheets When there is a large difference in the respective friction coefficients between the sheet feeding rollers, it is easier to perform an accurate feeding operation. Also, the friction coefficient must have the following relationship: "coefficient of friction between paper sheets"<"coefficient of friction between paper sheets and friction pad"<"coefficient of friction between paper sheets and paper feed roller" It is. However, if this relationship is satisfied, it is not always possible to separate one sheet, and depending on the paper quality and the like, a large margin is required for the difference between the friction coefficients.
[0008]
However, since paper dust and dust adhere to the surface of the paper feed roller, the coefficient of friction between the paper feed roller and paper sheets tends to decrease, and the stacked paper sheets are indefinitely intimately adhered to each other. There is a case where a so-called “non-feed” phenomenon occurs, in which even the uppermost paper sheet cannot be fed out due to the force. Here, the indeterminate adhesion between paper sheets means that the cut surfaces of the cut papers are in close contact with each other, the paper sheets containing moisture are once dried and stuck, or the paper sheets This is caused by the unevenness between the fibers of each other meshing. It also occurs in the case of paper sheets whose surfaces are coated with a resin and whose air permeability is reduced. If there is such a cause, even if the friction coefficient is set as described above, the paper feeding roller is idled, and the topmost paper sheet is not fed out and is not fed. The automatic paper feeding mechanism enters a halt state.
[0009]
The typical feeding failure in the automatic paper feeding mechanism includes the above-mentioned “non-feed” in which no sheet can be fed and “multiple feeding” in which a plurality of sheets are fed at once. There is one. In the case of double feeding, as long as the paper sheets are fed in close contact with each other, the automatic paper feeding mechanism does not enter a pause state. However, in the case of non-feeding, manual operations are required for returning, such as cleaning the paper feed roller and re-stacking the stack of stacked paper sheets, leading to a reduction in work efficiency.
[0010]
In recent years, networking of printers and the like has progressed, and there are many cases in which printing is performed by instructing from a location away from the printer. In such a case, once a non-feed occurs, the printer is in order to perform restoration work. It is necessary to go to the installation location of the network printer, which is contrary to the purpose of installing the network printer aiming at efficiency.
[0011]
The present invention has been made to solve the above problems, and the problem to be solved by the present invention is that even if a non-feed occurs, it automatically returns to a normal state without any manual operation and is in a non-feed state. This is to realize an automatic paper feeding mechanism that can eliminate the above problem with a simple configuration.
[0012]
[Means for Solving the Problems]
1 and FIG. 2 , the present invention for solving the above problems is in contact with the outer surface of the stacked paper sheets 10 and feeds out the outer paper sheets 10 (FIG. 1). In FIG. 2, since the uppermost paper sheet 11 is fed out, the outer peripheral surface of the paper feed roller 20 is brought into contact with the upper surface of the uppermost paper sheet 11 and the uppermost paper sheet 11 is fed out. However, since it is possible to easily take out the lowermost sheet, the expression of the outer surface of the stacked sheets is used), and the sheet feeding roller 20 is placed at the sheet feeding position by the sheet feeding roller 20. 20 is arranged in a state of being urged toward the outer peripheral surface of the paper 20, and contacts the paper sheet 10 fed out simultaneously with the paper sheet 11 on the outer surface. Automatic feeding mechanism with friction pad 50 blocked by Is the ash forms a part of a rotational force transmission path for transmitting the rotational output of the rotary drive source such as a motor to the paper feed roller 20 by an elastic member (spring).
[0013]
In the present invention, the rotation output of the rotation driving source to be transmitted to the paper feed roller 20 via the elastic body, the elastic body will be correspondingly with the delivered torque elastically deformed (twisted) to. With this configuration, in a situation where the sheet feeding roller 20 is not fed and the sheet feeding roller 20 cannot feed out the outer sheet 11, the sheet feeding roller 20 idles while directly contacting the friction pad 50.
[0014]
The frictional force between the paper supply roller 20 and the paper sheet 11 and the frictional force between the friction pad 50 and the paper supply roller 20 are large, and the friction between the paper supply roller 20 and the friction pad 50 (generally rubber) In other words, a phenomenon in which the boundary between the static friction coefficient and the dynamic friction coefficient becomes unclear is likely to occur. For this reason, at the time of idling, the torsional force is accumulated in the elastic body more than at the time of normal extension. When the accumulated torsional force exceeds the frictional resistance acting on the paper feed roller 20 and reaches the limit, the torsion of the elastic body returns all at once, so that the paper feed roller 20 rotates rapidly and the accumulated torsional force is increased. Release the twisting power at once. When the non-feed state continues, the torsional force accumulation and release cycle is repeated, and when viewed from the paper sheet 10 side, the rotation speed of the paper feed roller 20 is fluctuated. This intermittent change in the rotation speed of the paper feed roller 20 becomes an impact, and a kind of separation effect is produced on the paper sheet 10. As a result, the adhesion of the paper sheet 10 is canceled and the feeding of the outer paper sheet 11 is resumed.
[0015]
As described above, according to the present invention, even if a non-feed occurs, an automatic paper feed mechanism that can automatically return to a normal state and eliminate the non-feed state without a manual operation with a simple configuration. realizable.
[0016]
The present invention further includes a drive shaft that is coaxially disposed with the paper feed roller, is rotationally driven by a rotational drive source, and rotatably supports the paper feed roller, and the drive shaft and the paper feed roller. sealed, since that drive shaft relative to the paper feed roller having a spring as an elastic member that elastically deform when rotating relatively, thereby, facilitates placement of the elastic body.
[0018]
The spring has a middle portion fitted in a through-hole formed in the drive shaft in the radial direction , both ends are bent in an L shape, and the tip is locked in a hole formed in the end surface of the paper feed roller. A U-shaped wire spring . According to the present invention , the U-shaped wire spring is locked between the drive shaft and the paper feed roller, and thus can be configured more simply.
[0020]
[Embodiment]
(First embodiment)
A first embodiment will be described with reference to FIGS. Here, FIG. 1 is a side view showing the main part of the first embodiment, and FIG. 2 is a peripheral view of the paper feed roller as viewed from the left in FIG. In FIG. 1 and FIG. 2, the same reference numerals are given to the portions corresponding to FIG. 6 and FIG. It should be noted that the feeding out of the paper sheets includes not only a structure in which the uppermost paper sheet is fed out but also a structure in which the lowermost paper sheet is fed out. Although the present invention can be applied to any of them, the present embodiment has a configuration in which the outer peripheral surface of the paper feed roller is brought into contact with the upper surface of the uppermost paper sheet and the uppermost paper sheet is fed out. It is.
[0021]
Also in this embodiment, the paper sheets 10 are stacked on the paper feed table 30. The paper feed table 30 is biased upward (in the direction of arrow A) by a pressing means such as a spring (not shown), and the uppermost paper sheet 11 is pressed against the outer peripheral surface of the paper feed roller 20. Accordingly, the uppermost paper sheet 11 can be fed out by the paper feed roller 20 rotating counterclockwise (B direction) in FIG. Further, a friction pad 50 is disposed at the paper sheet feeding position by the paper feed roller 20 as in the case of FIGS. The friction pad 50 comes into contact with the paper sheet 10 fed out simultaneously with the uppermost paper sheet 11 in the paper sheet 10 and prevents a plurality of paper sheets 10 from being simultaneously fed out by a frictional force. It is.
[0022]
As the friction pad 50, generally, the friction coefficient between the friction pad 50 and the paper sheet 10 is slightly higher than the friction coefficient between the paper sheets 10, and between the paper feed roller 20 and the paper sheet 10. A material having a value lower than the friction coefficient is used. As a material, for example, an EPDM rubber plate, a foamed urethane rubber plate, a cork plate or the like having a JIS-A hardness of about 70 degrees is used. The friction pad 50 is supported so as to be movable in the direction of the outer peripheral surface of the paper feed roller 20 (in the direction of arrow C), and is further biased toward the outer peripheral surface of the paper feed roller 20 by a pressing means such as a spring (not shown). .
[0023]
The paper feed roller 20 in the present embodiment includes a cylindrical collar portion 21 that is rotatably fitted to a drive shaft 40 that rotates in the direction of arrow B, and a rubber ring that is fitted to the outer cylindrical surface of the collar portion 21. 22. The collar portion 21 is formed of a resin material such as POM having a small friction coefficient. Further, the paper feed roller 20 cannot be moved in the axial direction of the drive shaft 40 by a regulating means (not shown).
[0024]
The drive shaft 40 in this embodiment is rotatably driven by a rotation drive source such as a motor (not shown) while rotatably supporting the paper feed roller 20. A coil spring 60 as an elastic body is locked between the drive shaft 40 and the paper feed roller 20. When the drive shaft 40 rotates relative to the paper feed roller 20, the coil spring 60 is When the drive shaft 40 is elastically deformed and the drive shaft 40 rotates, a rotational drive force is transmitted from the drive shaft 40 to the paper feed roller 20 via the coil spring 60.
[0025]
The coil spring 60 has an inner diameter that is sufficiently larger than the outer diameter of the drive shaft 40 and is coaxially inserted into the drive shaft 40 with a clearance. One end 61 of the coil spring 60 is locked in the fixing hole 41 of the drive shaft 40. The other end 62 is locked in the fixing hole 25 at the side end of the paper feed roller 20. In this embodiment, the winding direction of the coil spring 60 is such that the inner diameter increases when the paper feed roller 20 is forcibly stopped and the drive shaft 40 is rotated in the direction of arrow B. Shaped in the direction. However, when the gap with the drive shaft 40 is large, the coil spring 60 does not clamp the drive shaft 40 even if the winding direction is reversed, so the winding direction is not concerned.
[0026]
Next, the operation of this embodiment will be described. When the first sheet (the uppermost sheet 11) is normally fed out, first, when the drive shaft 40 is rotated by a rotation drive source (not shown), the sheet feed roller 20 is rotationally driven via the coil spring 60. Power is transmitted. At this time, the two forces of the friction force between the friction pad 50 and the paper feed roller 20 and the friction force between the paper sheets 10 become the rotational load of the paper feed roller 20, and the coil spring 60 is stopped while the paper feed roller 20 is stopped. The torsional force is accumulated.
[0027]
When the feed roller 20 starts to rotate even a little after the balance point between the rotational load and the torsional force, the uppermost paper sheet 11 (or the second paper sheet 12 in some cases) ) Immediately enters the contact portion (nip portion) between the friction pad 50 and the paper feed roller 20, and thereafter, the rotational load applied to the paper feed roller 20 is the dynamic friction force between the friction pad 50 and the paper sheet 10, and the paper sheet. The dynamic friction force between the classes 10 is two. These two forces are much smaller than the force at the start of feeding, and the paper feed roller 20 smoothly feeds the uppermost paper sheet 11.
[0028]
On the other hand, when a non-feeding situation occurs, immediately after the rotation of the paper feed roller 20 is started in the case of normal feeding, the paper feed roller 20 moves on the paper sheet 11 due to the adhesion between the paper sheets 10. It is a case where it slips. When the paper feed roller 20 idles without feeding out the paper sheet 11, the friction pad 50 rotates for a while while being in direct contact with the paper feed roller 20. The frictional force between the sheet feeding roller 20 and the paper sheet 11 and between the friction pad 50 and the sheet feeding roller 20 is large, and the friction between the sheet feeding roller 20 and the friction pad 50 has a boundary between the static friction coefficient and the dynamic friction coefficient. The phenomenon of obscuring easily occurs.
[0029]
For this reason, during idling, the torsional force is accumulated in the coil spring 60 more than when it is normally extended. When the accumulated torsional force exceeds the frictional resistance acting on the paper feed roller 20 and reaches the limit, the torsion of the coil spring 60 returns all at once, so that the paper feed roller 20 slips and is higher than the drive shaft 40. It suddenly rotates at a speed and releases the accumulated torsional force at once. When the non-feed state continues, this cycle is repeated, and when viewed from the paper sheet 10 side, the rotation of the paper feed roller 20 becomes faster or the brake is suddenly applied.
[0030]
This intermittent rotation speed change of the paper feed roller 20 becomes an impact, and a kind of separation effect is produced for the paper sheet 10. As a result, the adhesion of the paper sheet 10 is eliminated, and the paper sheet 11 that has not been fed is fed out.
[0031]
The rotation state of the drive shaft 40 and the paper feed roller 20 according to this embodiment is shown in FIG. As can be seen from this figure, the drive shaft 40 is driven at a constant angular velocity, but the paper feed roller 20 is in an intermittent rotation state representing the function of the coil spring 60 and the non-linear friction characteristics.
[0032]
In order for the paper feed roller 20 to behave as shown in FIG. 3, the coil spring 60 is stopped by the braking by the frictional force acting on the paper feed roller 20 from the friction pad 50 and the drive shaft 40 is stopped. It is necessary for the strength to exist so that the rotation of the coil spring is present, and it is desirable to set the coil spring 60 so that the spring constant is not too large.
[0033]
As described above, in this embodiment, even if non-delivery occurs, it can be automatically restored to the normal state without any trouble. In addition, the configuration is extremely simple and causes almost no increase in cost.
(Second Embodiment)
FIG. 4 is a side view showing the main part of the second embodiment, and FIG. 5 is a view of the periphery of the paper feed roller as viewed from the left in FIG. 4 and 5, the same reference numerals are given to portions corresponding to those in FIGS. 1 and 2. The difference between the present embodiment and the first embodiment is that a U-shaped wire spring 70 is mainly used as a spring, and the configuration of other parts is the same as that of the first embodiment. .
[0034]
A through hole 42 is formed in the drive shaft 40 in the present embodiment in the radial direction. The U-shaped wire spring 70 has an intermediate portion inserted into the through hole 42 and the ends of both end portions 71 and 72 bent into an L shape are formed in the fixing holes 26 formed in the end surface of the paper feed roller 20. 27.
[0035]
Similarly to the coil spring 60 in the first embodiment, the U-shaped wire spring 70 according to the present embodiment is also locked between the drive shaft 40 and the paper feed roller 20. When the drive shaft 40 rotates relatively, it is elastically deformed. When the drive shaft 40 rotates, a rotational driving force is transmitted from the drive shaft 40 to the paper feed roller 20. Therefore, the operation of this embodiment is exactly the same as that of the first embodiment, and the U-shaped wire spring 70 of this embodiment bears the function of the coil spring 60 in the first embodiment. There is only. Therefore, the description of the operation of this embodiment is omitted.
[0036]
Even in this embodiment, even if non-feeding occurs, it can be automatically returned to the normal state without bothering people. In addition, the configuration is extremely simple and causes almost no increase in cost.
(Other embodiments)
The present invention is not limited to the configuration of the above embodiment. For example, the present invention includes the following embodiments.
(1) The basic idea of the present invention is that a part of the rotational force transmission path for transmitting the rotational output of the rotational drive source to the paper feed roller is made of an elastic body, and the part other than between the drive shaft and the paper feed roller. It is also possible to dispose an elastic body on. However, it is easiest in terms of layout to arrange an elastic body between the drive shaft and the paper feed roller.
(2) An elastic body other than a coil spring or a U-shaped wire spring can be used. For example, using a spiral spring, the inner end is locked to the drive shaft and the outer end is locked to the paper feed roller, or the drive shaft and the paper feed roller are arranged in a straight line so that they face each other A connection block made of an elastic material such as rubber is inserted between the end faces to be fixed.
(3) A belt winding mechanism is arranged in a rotational force transmission path for transmitting the rotational output of the rotational drive source to the paper feed roller, and the belt is made of an elastic body such as rubber.
{Circle around (4)} A backlash is provided at the fitting portion between the drive shaft and the paper feed roller to increase the impact caused by intermittent rotation speed change of the paper feed roller.
(5) Concerning the feeding of paper sheets, a configuration is adopted in which the lowermost paper sheet is fed, not the uppermost paper sheet.
[0037]
【The invention's effect】
As described above, according to the present invention, a part of the rotational force transmission path for transmitting the rotational output of the rotational drive source to the paper feed roller is formed of an elastic body. Thus, an automatic sheet feeding mechanism that can automatically return to the normal state without causing trouble and eliminate the non-feed state can be realized with a simple configuration.
[0038]
Further, according to the present invention, since the elastic body is disposed between the drive shaft and the paper feed roller, the elastic body can be easily disposed, and the U-shaped wire spring as the elastic body is connected to the drive shaft / paper feed roller. Since it locks in between, it can be configured more easily .
[Brief description of the drawings]
FIG. 1 is a side view showing a main part of a first embodiment.
FIG. 2 is a view showing the periphery of a sheet feeding roller as viewed from the left in FIG.
FIG. 3 is a diagram showing a rotation state of a drive shaft and a paper feed roller in the first embodiment.
FIG. 4 is a side view showing a main part of a second embodiment.
5 is a view showing the periphery of a sheet feeding roller as viewed from the left in FIG.
FIG. 6 is a side view showing a main part of a conventional automatic paper feeding mechanism.
7 is a front view seen from the right direction of FIG. 6;
FIG. 8 is a diagram illustrating the operation of a conventional automatic paper feeding mechanism.
[Explanation of symbols]
10 (11, 12) Paper sheets 20 Paper feed roller 21 Color section 22 Rubber ring 30 Paper feed table 40 Drive shaft 50 Friction pad 60 Coil spring 70 U-shaped wire spring

Claims (1)

A paper feed roller that contacts the outer surface of the stacked paper sheets and feeds out the paper sheets on the outer surface, and a paper sheet feeding position by the paper feed roller is biased toward the outer peripheral surface of the paper feed roller. Automatic feeding mechanism with a friction pad that is arranged in a state of contact and prevents a plurality of paper sheets from being simultaneously fed out by contacting with the paper sheets fed out simultaneously with the outer paper sheets. Because
A drive shaft that is coaxially disposed with the paper feed roller, is rotationally driven by a rotational drive source, and rotatably supports the paper feed roller;
An intermediate portion is inserted into a through hole formed in the drive shaft in a radial direction, both ends are bent in an L shape, and a tip is engaged with a hole formed in an end surface of the paper feed roller. An automatic paper feed mechanism comprising: a U-shaped wire spring that elastically deforms when the drive shaft rotates relative to a paper roller .

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